This application claims the priority of 196 13 915.5, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a method for economically repairing a mechanical defective spot on a new exterior paint coat of a motor vehicle.
German Patent 38 33 225 C2 describes a method for the locally point-limited repairing of paint defects in new paint coats on vehicle bodies. Specifically, the defective spot (for example, a particle inclusion, a small bubble or a thin spot because of an oil droplet on the background), is burned out by a focussed laser beam. The resulting small cavity is filled in on a small surface by a hardenable repair mass which matches the color of the surrounding paint, and a clear coating is applied also to a small surface. The repair mass is applied in different fashions.
Specifically, the following known methods are described in that document:
Locally targeted melting-open of a small quantity of repair mass by a focussed laser beam from a laid-on foil made of repair mass and simultaneous application of the melted-out quantity into the exposed cavity. PA1 Melting-open of the powdered repair mass pressed to form a small pellet, the pellet being placed on the cavity, and depositing such a small drop in the cavity. PA1 Depositing a small droplet of an originally liquid repair mass in the cavity, the droplet being guided into the cavity on the tip of a needle. PA1 In addition to the vehicle body part to be repaired and painted, the entire vehicle must be covered in a firmly adhering manner and, prior to that, temperature-sensitive inside and outside accessories must be demounted. Then, these parts must naturally be mounted again. This labor-intensive work is connected with high wage costs. PA1 Large amounts of covering foil are consumed which can be used only once. Apart from the consumption of foil, a large amount of garbage is created and results in unnecessary costs. PA1 Because of the multitude of vehicles to be repainted, a very large amount of space is required for the described preparation of the vehicles for the repainting. This requires high investment costs for corresponding large hangars and pieces of land. PA1 The demounting and mounting work itself causes possibilities of errors with respect to the function of the newly mounted parts. Furthermore, occasionally this work may cause new or additional damage to the paint. PA1 Just the size of the spot to be repainted may result in the possibility and probability of new defective paint spots. PA1 This large-surface repainting creates a relatively high demand for material and will also require a relatively large amount of time which also leads to correspondingly high costs for material and wages. PA1 The energy requirement for the baking and cooling of the large-surface new paint coats is correspondingly high so that stationary heat radiation tunnels with adjoining cooling tunnels are required. The corresponding investment costs and the continuous energy costs are therefore correspondingly high. PA1 (a) cleaning the damage spot and, without being ground out, laying out the spot with an excess of filler mass which approaches a finish paint coat in a color-determining shade such that an undamaged paint surface directly next to the spot remains free of filler mass, PA1 (b) levelling off a projection of the laid-out damage spot after the drying of the filler mass, PA1 (c) cleaning the levelled-off damage spot and applying a paint which, with respect to the color, corresponds to the finish paint coat to the damage spot on a small surface, which projects thinly over the damage spot on all sides thereof by approximately 4 to 6 cm, so as to have a thickness of approximately 10 to 20 .mu.m, (first repair finish paint layer 10), by guiding a spraying element radially and, centrifugally away from the damage spot, PA1 (d) ventilating or drying the applied paint in step (c) and then applying a transparent coat to the spot on a small surface, that is, projecting over the repainted surface on all sides by approximately 2 to 4 cm, PA1 (e) adjusting a transition area from the transparent coat application into the original finish paint coat by slight dissolving of the uppermost layer of original finish paint via a sprayed-on solutizer, and PA1 (f) locally drying the coats applied to the spot. PA1 Firmly adhering, total coverings of the vehicle and a demounting and subsequent mounting of temperature sensitive inside and outside accessories, as well as a covering or demounting/mounting of the also temperature-sensitive vehicle wheels, are not necessary. This work is very labor intensive and therefore connected with high wage costs which are now eliminated. PA1 As the result of the previously required, firmly adhering overall covering, large amounts of cover foil were used up which could be used only once. Apart from the high foil consumption, a large amount of garbage was generated in this manner which had to be disposed of at cost. Now, the vehicle body parts must only be covered in a firmly adhering manner at the repair spot over a small surface. The consumption of cover foil and adhesive tape as well as the corresponding garbage is reduced to a small fraction of the original quantities. In addition, cover paper can now be used which can be procured at a much lower price and can be disposed of at lower cost. If, during the repair, the vehicle must be covered over large surfaces, reusable cover parts can be used. PA1 The space requirement for the previously necessary covering and demounting/mounting was previously very high because of the large number of vehicles to be repainted which also led to high investment costs for corresponding hangar spaces. These costs will no longer be incurred. PA1 When a change takes place from an existing conventional repainting to the repainting according to the present invention, hangar space in the order of from approximately 15 to 20% of the surface requirement for the overall painting of vehicles becomes free and can be used for other purposes. PA1 Because of the elimination of the demounting and mounting work, a large amount of error possibilities with respect to the function of the newly mounted parts is eliminated. Furthermore, the previously required demounting and mounting of parts repeatedly resulted in new or additional damage to the paint. Because this work has now been eliminated, the rejection rate of the repainting is therefore reduced. PA1 Solely because of the smaller size of the spot to be repainted, the miniaturization of the spots to be repaired has the advantage that the possibility of new defective paint spots is significantly reduced in comparison to a large-surface repainting. Thereby, almost without exception, the paint coats repaired according to the invention are acceptable which is only partially true in the case of repaired large-surface paint coats. PA1 The requirement of material and time for the small-surface repainting is clearly reduced in comparison to the large-surface repair, and this leads to correspondingly lower costs for material and wages. PA1 The energy requirement for the baking and cooling of the small-surface repainting is correspondingly lower so that smaller heat radiators are required, for example, individual movable infrared radiators, in comparison to complete stationary heat radiation tunnels with adjoining cooling tunnels. As a result, apart from the above-mentioned lower space requirement, the respective investment costs for small heat radiators and, of course, also the continuous energy costs are clearly lower.
The hardening of the repair mass usually takes place thermally. However, the German patent document also mentions a hardening by UV-radiation. The repair mass and the clear coating can be hardened successively or, in the instance of a wet-in-wet application, may be hardened simultaneously. In any event, the hardening takes place by a locally targeted, small-surface addition of heat, for example, by a focussed, high-energy beam, by applying a hot gas by means of a nozzle, and by other methods. A possible projection of the applied repair mass above the cavity or a projection of the subsequently applied clear coating will be mechanically removed on a small surface.
By way of the repair, the locally disturbed paint layer is closed and, as a result, the protective function is restored also at the defective point. The repaired spot may also look better than the untreated defective paint spot and is less noticeable than the original paint defect. The known punctiform paint repair method has a disadvantage, however, in that it cannot completely visually remove the defective paint spot. That is, the repair spot can still be recognized at least when the demands on the paint coat are high and the paint coat is therefore critically inspected.
German Patent DE 40 09 000 A1 and German Patent DE 43 29 897 A1 describe a process for the multi-layer repair of a damage in a vehicle paint coat. Here, the defective spot in the multi-layer paint coat is first ground out down to the metal sheet, resulting in a ground spot of a diameter of approximately 5 cm. The ground-through spot is cleaned and is filled in with a known repair priming, thereby forming a film. The primed spot will then have a diameter of at least approximately 10 cm. A filler is applied to the priming in a film-forming manner. The repaired spot will then have a diameter of at least 15 cm. A paint layer in a covering layer thickness, which matches the color determining paint coat will then be applied to the filler layer, in which case the paint is applied so that, at the edge it will run out toward the old paint coat. A clear coating will then be applied over it which results in a further enlargement of the repair spot.
Before the application of the next layer, the individual applications are each ventilated to form a stable film or are partially dried. At least at the conclusion, the paint layers are jointly hardened at temperatures of above 100.degree. C. It is also suggested that a baking-in of individual layers can take place in-between.
This repair method has a disadvantage in that, with the recommended limitation of the application of the color-determining paint layer and of the clear coating layer to the repair spot, recognizable differences in color and brilliance occur in the transition area to the untreated old paint coat. These differences are particularly clearly noticeable especially with light metallic paints. For this reason, the customer cannot be expected to accept the repaired paint coat when used on exterior surfaces of the vehicle body according to the described method.
When repairing defects and damages on new paint coats in vehicle series production, it is therefore required and customary to coat the entire involved vehicle body part to the next body joint uniformly with the color determining paint layer and with the transparent coat in order to reliably exclude unattractive color edges around the repaired spot. Although damaged spots can be repaired in this manner which can then no longer be recognized, considerable expenditures are required for this purpose which are not easily recognizable. In particular:
Despite these cost disadvantages of large-surface repainting, small-surface repair painting is not known so far to have been accepted in practice for high-quality exterior paint coats because, with known repair painting methods, the repaired spots were always more or less easily recognizable.
It is, therefore, an object of the present invention to optimize a repair method such that damaged spots and small defective paint spots on new exterior paint coats of motor vehicles, on one hand, can be repaired at significantly lower costs and, on the other hand, without visually recognizable traces.
According to the present invention, this object has been achieved by providing a method in which
The decisive advantage of the present invention is a considerable cost saving effect which is based on the fact that the repair spot according to the invention can be kept small; that is, for example, below a diameter of from 20 to 25 cm. The breakthrough to a repaired and repainted spot which is small as well as perfect with respect to the painting technique was achieved on the basis of the method according to the invention as generally described above.
The repaired spot obtained according to the method of the present invention satisfies strict standards and withstands critical examination. This functional advantage, which can be achieved only as the result of the present invention, is, on one hand, also based on the small size of the repaired spot and, on the other hand, on the thin, possibly repeated application of the paint. This avoids cloudiness and disturbing edge or transition effects in an easily controllable manner. The repair of the damaged spot can no longer be recognized even by the trained eye, although the repaired spot changes over freely into the undisturbed surface of the vehicle body part or into the original paint coat.
The cost advantages which can be achieved by the repair method according to the invention are based on the following:
With the method according to the invention, not only small mechanical damage (as a rule, scratches or the like) can be effectively repaired at low cost, but the method is also suitable for repairing small paint defects which at first have no cavity but, on the contrary, enclose small particles or a small bubble in the solidified paint. If such a paint defect is carefully provided with a fine cavity and the defective spot is removed from the paint surface, the cavity can then be repaired like a mechanically damaged spot in the above-mentioned manner. The fine cavity can be produced mechanically or thermally.